In some kinds of rotary machines, the shafts or spindles to carry the rotational motions are driven to rotate at superhigh speeds which reach 30,000 to 50,000 revolutions per minute in the case of some textile production equipment such as for example roving frames, spinning frames and throwing machines. Such a superhigh speed rotation of a shaft or spindle imposes various exacting requirements on the bearing assembly to be used to support the shaft or spindle. One of these requirements is to cope with the wear and abrasion of the members and elements of the bearing assembly which are subject to sliding and rolling frictions concomitant with the superhigh speed rotation of the shaft or spindle supported by the bearing assembly.
A known bearing assembly which has been used for supporting the spindle of a textile production equipment such as typically a yarn wrapping machine is largely made up of an ordinary ball bearing consisting of inner and outer race members and spherical bearing elements interposed between the inner and outer race members. The shaft or spindle to be supported by such a bearing assembly is securely connected to the inner race member of the ball bearing so that the shaft or spindle and the inner race member of the bearing are to be driven to rotate as a single unit about the center axis of the shaft or spindle with respect to the outer race member fixed to a suitable stationary structure. Thus, the inner race member of the ball bearing is driven to rotate at a speed equal to the speed of rotation of the shaft or spindle supported by the bearing assembly and, for this reason, the maximum speed of rotation allowable of the shaft or spindle is limited by the wear and abrasion resistance of the ball bearing.
In the field of machine engineering, it is known that ball bearings in general tend to be critically worn out to such an extent as to be no longer serviceable when subjected to continuous rotation at speeds exceeding about 15,000 revolutions per minute. With the rotational mechanism in which the shaft or spindle is connected to the inner race member of a ball bearing, therefore, the shaft or spindle must be driven for rotation at a speed lower than 15,000 revolutions per minute. This has brought forth a bar to increasing the performance efficiency or achieving the desired performance efficiency of, for example, a yarn wrapping machine.
It is, accordingly, a prime object of the present invention to provide a bearing assembly which is capable of withstanding the rotation at speeds higher than 30,000 revolutions per minute and maintaining a shaft, spindle or the like in a stable condition for an extended period of time.
It is another object of the present invention to provide a bearing assembly in which the revolution speed of the shaft or spindle supported by the bearing assembly is transmitted, upon reduction, to the rotary member of a bearing forming part of the bearing assembly so that the shaft or spindle can be driven to rotate at a speed higher in a desired ration than the upper limit of the acceptable range of the revolution speed of the bearing assembly.
It is still another object of the present invention to provide a bearing assembly which is constructed and arranged in such a manner that the loads imparted to the bearing assembly in radial directions from the shaft or spindle supported by the bearing assembly so that the shaft or spindle is maintained in a correct coaxial position with respect to the bearing assembly and is prevented from being caused to sway or laterally oscillate during superhigh speed rotation of the shaft or spindle.
It is still another object of the present invention to provide a bearing assembly in which the impacts and vibrations which may be transferred to the bearing assembly from the shaft or spindle supported by the bearing assembly can be efficiently dampened out so that the shaft or spindle is enabled to rotate smoothly and noiselessly in the bearing assembly.
Yet, it is another object of the present invention to provide a superhigh speed bearing assembly which is simple in construction and economical to manufacture and to maintain and service.